Woot

Might not mean much to you up there near the equator though ...

http://en.wikipedia.org/wiki/Winter_solstice

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bl..dy wiccans.....thy're everywhere....

Thought I'd share this with you

The winter solstice (for us 21 June) is the point at which the apparent orbit of the sun changes and it starts heading south. On 21 June its over the Tropic of Cancer (northern hemisphere).

Our summer solstice (for us 21 December) is the point at which the apparent orbit of the sun changes and starts to head north.

The word tropic comes from the greek tropos - to turn. Hence the 2 tropics.

The word capricorn comes from latin words ( caper - the goat and cornu - horn). Cancer will have a similarly based origin.

So why does the sun appear to move?

It doesn't. It seems to move because the earth's axis is inclined at 23 degrees 27 minutes . This tilt means that different parts of the earth's surface are closest to the sun in 1 complete orbit of 365 days.

To make it more complicated, the earth also wobbles on its axis as it spins in 24 hrs. The spin is from the effects of precession and nutation. (All of you microwave experts will be familar with the term precession and YIG filters).

Instead of having a relatively static effect, nutation and precession have increasing and/or decreasing effects.

That simply means that the tropics are constantly changing. Slowly with the effects of nutation and faster with the effects of precession.

You can't put a marker on the ground and say " that's the Tropic of Capricorn" 'cos in 12 month's time it'll be wrong.

There used to be a marker (a huge sundial in the shape of a tall spire) on the old highway just south of Rockhampton. In the mid 70s, the spire was isolated by highway diversion.

The marker was shifted into Rockhampton to a shady park next to the Tourist Information centre on Gladstone Rd.

With the days of GPS navigators, we now get southern tourists marching into the spire centre to confidently tell us that the spire marker is in the wrong place (country bumkins getting it wrong stuff).

Then follows a discussion about nutation and precession with the tourist departing scratching their heads and no longer sure about trusting what the GPS says.

At the Capricorn Caves just north of Rocky, there is a natural cleft in a rockface allowing a 1-2 day "window" either side of 21 Dec for the overhead sun's rays to shine down the "pipe" into the cavern some 10 metres below ground.

A mirrorball has been placed in the right spot and it reflects the sun's rays all around the cave. Some people come a long way to see the effect only for that short period.

Question.

Does the same constantly changing angle of the earth have the same effect on the Equator and the Arctic and Antartic circles? Do they move?

Is it the effects of naturally occuring nutation and precession that are the real causes of climate change??

It means alot to me Matt. It means the daytime spring lows will get below 2m again. Mmmm harbour barra.

Fish Tank I agree can't happen soon enough! If the tinny is out of the water any longer it'll get osmosis or some other terrible disease

ronje.....if i ever turn up to a quiz night make sure i take you...couldnt lose with u at the table !!!!

Well there ya go.. I thought nutation was the removal of ya nuts.. and precession was the pissup beforehand. Learn sumthin new every day.

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Fish Tank

It also means that the tidal variations and predictions will change as the earth's tilt changes. Apart from presenting different surface area to the sun, it'll also present a different surface area to the moon. That means that the moon's gravitational pull will affect the earth's oceans differently.

U may very well end up with no tides for six months of the year and tides bigger than what u get now for the other 6 months. That'll fix your neaps and springs.

But never mind. Juliar will fix everything with her carbon tax.

It'll move the earth for you and fix the earth's changing tilt!

So tell us about the polar circles and the equator.

Must say we are looking forward to paying more tax .... Yeah right.

Of course it will reduce CO2 production (in Australia at least) 'cause it will send industry overseas, then we can all feel good about about ourselves leading the world in carbon reduction!

Oh sorry, you were talking about the solstice....... Silly me.

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As long as we all retain a sense of humour.

What are you on about ronje?

Hhahaha, I'm with you mate, haaa always learnin I guess